JPH1032999A - Method and apparatus for automatic voltage control of generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost control apparatus, by which a change in an output voltage due to a change in a load is controlled quickly, and by which a stable specified voltage is held. SOLUTION: A rectifying circuit 6 by which the output voltage of a generator 2 is converted into a feedback voltage is installed. A current transformer 8 which detects a load current is installed. A compensation rectifying circuit 9 by which a current proportional to the load current obtained from the current transformer 8 is converted into a DC compensation voltage is installed. An addition circuit 10 which outputs the sum voltage of the feedback voltage and the compensation voltage is installed. A comparator circuit 11 to which the sum voltage of the addition circuit 10 and a predetermined reference voltage are inputted, and which controls a generator field current on the basis of the reference voltage is installed. A field current is controlled on the basis of the signal output of the comparator circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic voltage control device which is controlled in accordance with a change in load and which can obtain a stable output voltage of a generator.

[0002]

2. Description of the Related Art The control system of an automatic voltage control device for a generator is roughly classified into three types: proportional control, integral control and differential control. Or a special current transformer (C
T) and a method of feeding back a voltage or current proportional to the load current to the field winding is often used.

[0003] Proportional control is a system in which a value obtained by appropriately dividing the power generation output is compared with a reference voltage, and a value proportional to the deviation voltage is fed back. In this proportional control, when the load current fluctuates stepwise, the output voltage fluctuates to a steady value after a certain period of time. However, if the proportional control is performed as shown in FIG. The deviation from the reference voltage is compensated for by the exciting current increasing operation to reduce the deviation to zero.However, the exciting current is changed by non-linear elements such as a voltage drop of the armature winding due to the fluctuating load and parameter elements.
It is not possible to follow the fluctuation of the output voltage to a level that completely compensates for the fluctuation, and the output voltage is stabilized at a voltage value somewhat lower than the reference voltage as a steady-state error.

The integral control is a method of controlling a deviation voltage between an output voltage and a reference voltage to a magnitude proportional to an integral constant value. In this method, the excitation current is adjusted as long as there is a deviation voltage, so the output voltage eventually reaches the reference value, but the transient response is slightly inferior because the integral operation is performed immediately after the load current changes stepwise. As shown in FIG. 2, the fluctuation of the output voltage is larger than in the other methods.

Further, the differential control is a method of controlling a deviation voltage between an output voltage and a reference voltage according to a differential constant value. In this method, a large deviation output peculiar to the differential characteristic is obtained with a deviation voltage in which the load current changes stepwise, but a steady value is stabilized at an output voltage that is not controlled as shown in FIG.

[0006] Therefore, these components are not separately constituted independently, but are generally constituted in combination so as to make use of their respective features. For example, the compensation control for the steady-state error is configured by combining the proportional control and the integral control, and considering the responsiveness, the control is configured by combining the proportional control, the integral control, and the differential control.

On the other hand, a configuration shown in FIG. 4 is often used as a system in which a field control CT and a constant voltage control device are used in combination. That is, two field windings are required. Also,
There is also used a method in which a field winding applies a current proportional to each of an output voltage and a load current as a one-circuit system.
These require expensive control CTs, but have performances such as a simple circuit configuration, a small voltage fluctuation rate, and good transient characteristics.

In general, when a commercial power supply and a generator are operated in parallel, a current transformer is also used in a control circuit for reducing the generated cross current to zero. The synthesis of the voltage proportional to the cross current is performed on the AC side, and the configuration and operation thereof are different from those of the present invention, and are not intended to keep the output voltage during the single operation of the generator constant. . In addition, there is a method of compensating for a voltage drop due to a load current by flowing a rectified current proportional to a load current to a field winding of a generator using a current transformer as a power supply. Is large, the current transformer has a large capacity.

[0009]

The proportional control, the integral control, and the differential control are not used independently, but are configured in combination. However, these designs have many difficult parts such as determination of parameters. The circuit design has many elements of trial and error, and the circuit configuration has become complicated and expensive in the end. In the case of using the field control CT and the constant voltage controller in combination, the load on the field winding is large.
Since the control CT has a large capacity and requires a space for it, and has a disadvantage of being very expensive, a small and inexpensive apparatus while maintaining or improving the performance is desired. I have.

By the way, the AVR system of the generator is generally constructed using an integrated circuit for a switching regulator. However, at present, there is no room for adjustment when the deviation voltage between the output voltage and the reference voltage does not become zero due to a large load change or the like, that is, when a steady-state deviation occurs.

From the above, it is possible to provide an automatic voltage control device capable of suppressing the fluctuation of the generator output voltage due to the load fluctuation without a steady-state deviation, and to reduce the capacity of the detection control CT for obtaining the compensation voltage according to the load current. It is an object of the present invention to make it possible to reduce the size of the entire apparatus by making it possible to detect it at a low cost.

[0012]

According to the present invention, a feedback voltage obtained by rectifying an output voltage of a generator and a compensation voltage obtained by rectifying a current proportional to a load current are defined as a sum voltage. Means for solving the above-mentioned problems are provided by an automatic generator voltage control method for controlling a generator field current based on a deviation from a reference voltage.

More specifically, the present invention relates to an automatic voltage regulator for a generator capable of stably supplying a generator output voltage, comprising a rectifier circuit for obtaining a feedback voltage from the generator output voltage. A current transformer for detecting a load current and a compensation rectifier circuit for converting a current proportional to the load current obtained from the current transformer into a DC compensation voltage, and a sum voltage of the feedback voltage and the compensation voltage. And a comparator circuit which receives the output of the addition circuit and a predetermined reference voltage and outputs a signal according to the magnitude of the reference voltage. The signal output of the comparator circuit is provided. The above-mentioned problem is solved by controlling the exciting current.

Further, the adder circuit outputs a sum voltage by connecting a feedback voltage and a compensation voltage to opposite polarities, and the current transformer detects a load current of a generator. The fact that the current transformer for the current meter is also used is also an effective means.

The stator has a power generation winding and an excitation winding having a different number of poles from the power generation winding, and has a field winding which enables magnetic coupling with the excitation winding. In a generator including a rotor that forms magnetic poles that are magnetically coupled, by controlling the field of the rotor by controlling the exciting current of the exciting winding, the automatic voltage control device of the present invention is a brushless It can be added to the generator.

[0016]

According to the present invention, the feedback voltage obtained from the output voltage and the compensation voltage obtained by rectifying the current proportional to the load current are simultaneously detected, and the sum voltage is outputted, so that the voltage is apparently determined in advance. The difference between the specified reference voltage and the expanded voltage is input to the comparator, and the field current is controlled according to the magnitude of the reference voltage to eliminate the fluctuation range of the output voltage due to the load fluctuation of the generator. The voltage is controlled so that the voltage can be maintained.

That is, in the conventional proportional control, a feedback voltage obtained by converting the generator output and a predetermined reference voltage are inputted to a comparator or the like, and the feedback obtained here is obtained.
Although the field current is controlled by the difference between the feedback voltage and the reference voltage, the difference between the output voltage of the generator and the rated voltage generated by the conventional control does not become zero with a certain difference. The output voltage does not reach the specified voltage.
The problem is solved by detecting the sum voltage obtained by adding the compensation voltage obtained from the load current to the feedback voltage obtained by converting the generator output. This is because the compensation voltage is added to the feedback voltage and the sum voltage is input to the comparator, so that the voltage is expanded and compensated, so that the deviation voltage is compensated.
A specified output voltage can be obtained.

The addition of the compensation voltage to the feedback voltage obtained from the output voltage can be realized, for example, by adding the compensation voltage to the feedback voltage with a polarity opposite to that of the feedback voltage. In other words, when the compensation voltage is applied to the feedback voltage in the opposite polarity, the feedback voltage acts so as to be smaller, and the voltage compensated by this addition is input to the comparator. And the field current is controlled to be larger. As a result, the output voltage also changes greatly, so that the decrease in the output voltage due to the steady-state error in the conventional proportional control is eliminated.

Furthermore, a complicated and expensive device such as integral control, differential control, or a combination thereof is not provided. A compensation rectifier circuit is provided which inputs a current from a current transformer such as a current meter and rectifies the current. This can be achieved by a very simple circuit in which the output is added as a compensation voltage to a feedback voltage obtained from the output voltage.

In general, when a commercial power supply and a generator are operated in parallel, a current transformer is also used in a control circuit for reducing the generated cross current to zero. The synthesis of the voltage proportional to the cross current is performed on the AC side, and the configuration and operation thereof are different from those of the present invention, and are not intended to keep the output voltage during the single operation of the generator constant. . In addition, there is a method of compensating for a voltage drop due to a load current by flowing a rectified current proportional to a load current to a field winding of a generator using a current transformer as a power supply. Is large, the current transformer has a large capacity.

Since it can be added to a brushless synchronous generator,
Considering convenience such as maintenance of brushless synchronous generators, generators have been added as inexpensive generators that can supply voltage stably by adding an inexpensive voltage controller that can clear steady-state errors. Can contribute to any field that requires

[0022]

FIG. 5 shows a preferred embodiment of the present invention.
This will be described below. FIG. 5 is a circuit diagram schematically showing the connection between the generator automatic voltage control device 1 and the generator 2 according to the present invention. The generator denoted by reference numeral 2 has a main power generation winding 3 and a field winding 4 as main components, and a load 5 is connected to an output terminal of the main power generation winding 3. Each of the three-phase output lines shown in the drawing is connected to a rectifier circuit 6 composed of, for example, a diode. The output of the rectifier circuit 6 is connected to an output voltage divider 7 composed of at least two resistors r. It is grounded via a resistor R for obtaining a compensation voltage described later.

A current transformer 8 for detecting a load current is provided.
The output is used as a compensation rectifier 9 composed of, for example, a diode.
, And the (−) output of the compensation rectifier circuit 9 is input to a connection point between the resistor r and the resistor R. The resistor r and the resistor R form an adder circuit 10. That is, the output of the compensation rectifier circuit 9 is input to the adder circuit 10. Further, the potential position of the output voltage divider 7 is used as an output for comparison.
The comparator circuit 11 receives a reference voltage as a comparison reference. By the way, the current transformer 8 can also serve as an instrument CT used for an ammeter, so that there is no need to provide a separate current transformer.
With the configuration described above, the output voltage does not stabilize at a value lower than the specified voltage and becomes the specified output voltage, unlike the contents described in the section of the related art and the problem.

Therefore, in the present invention, the compensation rectifier circuit 9 is provided in addition to the proportional control. The output of the compensation rectification circuit 9 is input to the addition circuit 10, and the (−) of the compensation rectification circuit 9
Since the output side is connected, the compensation voltage obtained by rectifying the current that changes in accordance with the change in the load current is input to the addition circuit 10 as a change in the voltage in accordance with the change in the load. In 10, the voltage drop of the feedback voltage by the rectifier circuit 6 is added to the voltage drop of the compensation voltage of the compensation rectifier circuit 9 with the opposite polarity, and the sum voltage having different polarities is obtained by subtracting the difference between both voltages from the adder circuit. Output, which is lower than the actual feedback voltage and
The comparator circuit 11 calculates the difference between the voltage drop of the adder circuit 10 compensated by the voltage of the compensation rectifier circuit 9 and the reference voltage of the comparator circuit 11. The excitation current of the field winding is increased or decreased in accordance with the magnitude of the generated voltage, so that the output voltage and the reference voltage, which cannot be controlled by the proportional control, can be achieved by adding the compensation voltage.

Incidentally, the rectifier circuit 6 and the compensation rectifier circuit 9 are preferably constituted by rectifier circuits such as diodes. In addition, by connecting the rectifier circuit 6 and each of the three-phase output lines via a transformer, a stable and appropriate voltage can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. Here, the output voltage is transformed by the three-phase transformer 12 instead of the output voltage divider 7 to obtain a feedback voltage. The difference between the output voltage divider 7 and the transformer in FIG. 5 is that the advantage of the transformer is that no matter how small the voltage on the output side of the transformer is, the voltage on the input side of the transformer is converted to the rated voltage on the output side. Is output. However, the output voltage divider 7 divided by a resistor has a divided voltage value of the output voltage, which is not only easily affected by fluctuations in the power supply, but also an output rectified voltage obtained by rectifying the generator output voltage, for example, 300 V. 7
Since the gain is low to divide the voltage to V, the error increases. The output of the three-phase transformer 12 is input to the three-phase rectifier circuit 6, and the output of the three-phase rectifier circuit 6 is connected to the adder circuit 10 via a resistor.

In the adder circuit 10, a variable resistor VR1 for adjusting the voltage input to the circuit, a resistor r of the voltage drop on the feedback voltage side and a resistor R of the voltage drop on the compensation voltage side are added in series. Is provided with a resistor circuit 13 connected to the resistor. This adding circuit 10 is a resistor circuit 13 for adding the voltage drop on the feedback voltage side and the voltage drop on the compensation voltage side.
And the variable resistors VR1 and VR2 and a resistor provided between the three-phase rectifier circuit 6 and the adder circuit 10.

On the other hand, the load current is detected by a current transformer 8 provided on a three-phase output line, for example, a CT for an instrument, and is input to a three-phase rectifier circuit 9 by detecting a current proportional to the load current. The (+) side of the three-phase rectifier circuit 9 is grounded via a capacitance, and the (-) side of the three-phase rectifier circuit 9 is input to the above-described adder circuit 10 via a variable resistor VR2. A resistor is provided in parallel with the output terminal of the rectifier circuit 9 to prevent the current transformer from being damaged.

As shown in FIG. 7, the polarity of the voltage V1 on the feedback voltage side and the polarity of the voltage V2 on the compensation voltage side are input in opposite polarities. For example, the feedback voltage V1 side is about 7V. The variable resistors Vr1 and Vr are set so that the compensation voltage V2 side has a voltage drop of about 0.4 V due to the voltage drop of
r2, the voltage drop of the adder circuit 10 is (V1
-V2) is 6.6 V. The voltage drop 6.6 V at this time is connected to the adder circuit 10 so as to be inputted to the comparator circuit 11.

Returning to FIG. 6, the comparator circuit 11
Is a switching type regulator which compares a preset reference voltage, for example, 7V, with an input voltage of 6.6V to determine whether it is higher or lower than the reference voltage. When the value is larger than the reference, the switching of the comparator is ON, and when the value is smaller than the reference, the switching of the comparator is OFF. That is, when a voltage of 6.6 V is input, the comparator
The switching of the tar is OFF. Comparing
When the transistor is OFF, the transistor Tr1 connected to the comparator output does not turn on. Therefore, the transistor Tr2 connected by the resistor R0 turns on, and the next transistor Tr3 turns on. The excitation winding circuit 14 is connected to a power supply to excite the field. On the other hand, when the switching of the comparator is ON, that is, when the voltage drop is larger than the reference voltage, the transistor Tr1 is turned ON, and the resistor R0 is grounded through the transistor Tr1. Therefore, since the other transistor elements Tr2 and Tr3 do not turn on, no current flows through the excitation circuit 14.

As described above, the feedback voltage and the compensation voltage are added by the adding circuit 10, and the sum voltage due to the voltage drop and the preset reference voltage are compared with each other by the comparator.
The comparison is performed by the circuit 11, and the excitation circuit 14 is controlled to be turned off or on depending on whether it is larger or smaller than the reference.

FIG. 8 shows a simplified connection diagram between the automatic voltage control device of the present invention and a generator. In this configuration, a generator winding 16 and an excitation winding 17 having a different number of poles from the generator winding 16 are provided on the stator 15 side, and the excitation winding 17 can be magnetically coupled to the rotor 20 side. In addition, a rotor winding 19 in which a plurality of windings each having an electric angle of 180 degrees are wound via a semiconductor element 18 so as to form a magnetic pole magnetically coupled with the power generation winding 16 is provided. In this generator, the field pole of the rotor is controlled by the exciting current of the exciting winding 17, that is, by the automatic voltage controller of the present invention. This is a brushless synchronous generator that is easy to maintain, and is shown in a configuration in which an automatic voltage control device having a compensation rectifier circuit added to an automatic voltage control device is connected. As described above, the automatic voltage control device of the present invention can be connected to the brushless synchronous generator, and the brushless synchronous generator can greatly contribute to improvement of performance as well as maintenance.

FIG. 9 shows a characteristic diagram of the output voltage and the exciting current of the brushless synchronous generator provided with the automatic voltage control device according to the present invention. As is apparent from FIG. 9, the output voltage that matches the specified voltage is maintained even when the load current changes. Even if the load is changed from no load to the connected state, the voltage fluctuates at the moment of the change, but the fluctuation time is within 0.2 seconds, which is practically acceptable, and the output voltage is controlled to the specified voltage. You can see that it is.

[0034]

According to the present invention, it is possible to eliminate the fluctuation range of the output voltage due to the load fluctuation of the generator and to perform the voltage control so that the specified voltage can be always maintained. Moreover, it does not become a complicated and expensive device such as integral control, differential control, or a combination of these. Is added to the feedback voltage obtained from the output voltage as a compensation voltage.

Since it can be added to the brushless synchronous generator, considering the convenience of maintenance of the brushless synchronous generator, etc., a voltage control device which is inexpensive and can clear the steady-state deviation is added, and the voltage is supplied stably. It can contribute to any field where a generator is needed as a cheaper generator.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram of an output voltage and an exciting current in a conventional proportional control.

FIG. 2 is a characteristic diagram of an output voltage and an exciting current in a conventional integration control.

FIG. 3 is a characteristic diagram of an output voltage and an exciting current in a conventional differential control.

FIG. 4 is a circuit diagram in which field control CT is used together with conventional control.

FIG. 5 is a circuit diagram of an automatic voltage control device according to the present invention.

FIG. 6 is a more detailed circuit diagram of the automatic voltage control device of the present invention.

FIG. 7 is a diagram showing an adding circuit of the automatic voltage control device according to the present invention.

FIG. 8 is a circuit diagram in which the automatic voltage control device of the present invention is applied to a brushless synchronous generator.

FIG. 9 is a characteristic diagram of an output voltage and an exciting current when the automatic voltage control device of the present invention is provided and operated in a brushless synchronous generator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 automatic voltage controller 2 generator 3 main generator winding 4 field winding 5 load 6 rectifier circuit 7 output voltage divider 8 current transformer 9 compensation rectifier circuit 10 addition circuit 11 comparator circuit 12 three-phase transformer 13 Resistance circuit 14 Stator excitation circuit 15 Stator 16 Generator winding 17 Excitation winding 18 Semiconductor element 19 Rotor winding 20 Rotor 20 r Resistance R Resistance R0 Resistance VR1 Variable resistance VR2 Variable resistance Tr1 Transistor element Tr2 Transistor element Tr3 Transistor element

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[Procedure amendment]

[Submission date] August 29, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

On the other hand, the load current is detected by a current transformer 8 provided on a three-phase output line, for example, a CT for an instrument, and is input to a three-phase rectifier circuit 9 by detecting a current proportional to the load current. The (+) side of the three-phase rectifier circuit 9 is grounded, and the (-) side of the three-phase rectifier circuit 9 is input to the above-described adder circuit 10 via the variable resistor VR2. Further, a capacitance and a resistance are provided in parallel with the output terminal of the rectifier circuit 9 to prevent the current transformer from being damaged and to reduce the load .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

Returning to FIG. 6, the comparator circuit 11
Is a switching type regulator, which compares a preset reference voltage, for example, 7V, with an input voltage of 6.6V to determine whether the voltage is higher or lower than the reference voltage. In this case, the switching of the comparator is ON, and when it is smaller than the reference, the switching of the comparator is OFF. That is, when a voltage of 6.6 V is input, the switching of the comparator is OFF. When the comparator is OFF, the transistor element Tr1 to which the comparator output is connected does not turn ON. Therefore, the transistor element Tr2 connected by the resistor R0 turns ON, and the next transistor element Tr3 turns ON, thereby setting the stator excitation winding. The line circuit 14 is connected to a power supply to energize the field. On the other hand, when the switching of the comparator is ON, that is, when the comparator 10
When the input voltage to the comparator circuit 11 is higher, the transistor element Tr1 is turned on, so that the resistor R0
Is grounded through this transistor element Tr1. Therefore, since the other transistor elements Tr2 and Tr3 are not turned on, no current flows through the excitation circuit 14.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

As described above, the feedback voltage and the compensation voltage are added by the adding circuit 10 to obtain a sum voltage, and the sum voltage is compared with a preset reference voltage by the comparator circuit 11. The excitation circuit 14 is controlled to be turned off or on depending on whether it is large or small.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

FIG. 9 shows a characteristic diagram of the output voltage and the load current of the brushless synchronous generator provided with the automatic voltage control device according to the present invention. As is apparent from FIG. 9, the output voltage that matches the specified voltage is maintained even when the load current changes. Further, even if the load is changed from a no-load state to a connected state, the voltage fluctuates at the moment of the change, but the fluctuation and the fluctuation time are small, for example, within 0.2 seconds, and are practically practical.
It can be seen that the output voltage is also controlled to the specified voltage.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

[0034]

According to the present invention, it is possible to eliminate the fluctuation range of the output voltage due to the load fluctuation of the generator and to perform the voltage control so that the specified voltage can be always maintained. Moreover, it does not become a complicated and expensive device such as integral control, differential control, or a combination of these. Instead, a current is input from a current transformer such as a current meter , and a compensating rectifier circuit is provided to rectify the current. Can be achieved with a very simple circuit of adding the feedback voltage obtained from the output voltage.

[Procedure amendment 6]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

[Procedure amendment 7]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

[Procedure amendment 8]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7

Claims (5)

[Claims] 1. A generator according to a deviation of a sum voltage of a feedback voltage obtained by rectifying an output voltage of a generator, a compensation voltage obtained by rectifying a current proportional to a load current, and a predetermined reference voltage. An automatic voltage control method for a generator, comprising controlling a field current. 2. An automatic voltage regulator for a generator capable of stably supplying a generator output voltage, comprising: a rectifier circuit for obtaining a feedback voltage from the generator output voltage; A current transformer to be detected and a compensation rectifier circuit for converting a current proportional to a load current obtained from the current transformer into a DC compensation voltage are provided, and an addition for outputting a sum voltage of the feedback voltage and the compensation voltage is provided. A circuit and a comparator circuit for receiving an output of the adder circuit and a predetermined reference voltage and outputting a signal depending on the magnitude of the reference voltage.
An automatic voltage control device for a generator, wherein an exciting current is controlled by a signal output of the comparator circuit. 3. The automatic voltage control of a generator according to claim 2, wherein the adder circuit outputs the sum voltage by connecting the feedback voltage and the compensation voltage in opposite polarities. apparatus. 4. The automatic voltage control device for a generator according to claim 2, wherein the current transformer also serves as a current meter current transformer for detecting a load current of the generator. 5. A generator winding comprising: a stator provided with a generator winding and an exciting winding having a different number of poles from the generator winding; and a field winding enabling magnetic coupling with the exciting winding. 3. The generator according to claim 2, wherein in a generator including a wire and a rotor that forms a magnetic pole that is magnetically coupled, a field of the rotor is controlled by controlling an exciting current of the exciting winding. 4. Automatic voltage control of generator.